As of 10:30 pm Tuesday, the race was still too close to call. Lamb was at 49.8 percent and Saccone was at 49.6 percent, with 98 percent of precincts reporting.

Right now there’s a possibility that there could be a recount, although it likely would not happen for the next few days.

How does a Pennsylvania recount work?

Under Pennsylvania state law, if one candidate wins an election by less than half of a percentage point, all counties must start a recount.

But there’s a catch — PA-18 is an election for just one district, not the entire state. That means no mandatory recount is triggered, according to the Pennsylvania secretary of state’s office.

Petitions to have a recount are allowed, and voters have five days to file them, according to CNN’s David Wright.

Pennsylvania Sec. of State spokesperson Wanda Murren tells CNN that b/c this is a district race & not statewide, there is no mandatory recount here. Petitions are allowed, which require 3 voters in each precinct; have 5 days to file after the county completes its computation.

If a recount were to happen, it wouldn’t be for a few days, according to Pennsylvania election lawyer Adam Bonin.

If I have to, I’ll explain. Promise. But the first important thing to know is that this is not a count tonight; it’s unofficial and does not include absentee or provisional ballots. The formal count begins Friday, & overseas/military absentees have until next Tues to come in. https://t.co/M43ENosfZk

Back in 2016, the state was requested to start a recount by the Green Party’s Jill Stein after the 2016 presidential election, to make sure none of the state’s electronic voting equipment was tampered with (the request was denied by a judge).

Pennsylvania’s voting machines are fairly outdated, and last month, Gov. Tom Wolf, a Democrat, ordered that the state replace its old voting machines with newer ones that can leave a paper trail, as a safeguard against hacking. It would cost about $60 million to replace all of them, according to the website Engadget.

But Wolf’s operating budget didn’t include any money for the new machines, which means a lot of counties are still operating with the old ones.

This is an extremely tight race — which is bad for Republicans

On its face, Tuesday’s special congressional election in the southwest corner of Pennsylvania was supposed to be a breeze for the GOP, which has held this seat since 2003. The Cook Political Report rates the district R+11 (due in part to partisan gerrymandering that the state Supreme Court recently ruled unconstitutional).

But now it’s looking like Lamb is in a dead heat with Saccone. Last week, the Cook Political Report declared the race a toss-up, moving it away from its previous “lean Republican” rating.

Saccone was supposed to walk away with a win in a district Trump won by 20 points in 2016. The fact that he could lose it by a hair is bad, but even if he pulls out a win by a fraction, pollsters agree it’s still a bad sign for GOP chances in 2018.